Bus structure for power switching circuits

ABSTRACT

A bus system is disclosed for use with switching devices, such as power electronic devices. The system includes generally parallel bus elements that define electrical reference planes, such as for a dc bus. The bus elements are separated from one another by insulative layers, with additional insulative layers being available for separating the system from other circuit components. Portions of the bus elements are extended or exposed to permit connection to the circuit elements, including packaged switching circuits and energy storage or filtering circuits. The bus system may be conformed to a variety of geometric configurations, and substantially reduces parasitic inductance and total loop inductance in the resulting circuitry.

BACKGROUND OF THE INVENTION

The present application relates generally to the field of powerelectronics and power switching devices. More particularly, theinvention relates to a novel bus structure for use in such devices toreduce parasitic inductance.

Many applications exist for power electronic devices, including solidstate switches. Such applications are found throughout the industry, andincreasingly in non-industrial settings as well. In general, solid stateswitches may be used in a variety of circuitry, such as in invertercircuits that simulate desired waveforms, such as ac waveforms. Inindustrial drive applications, for example, power may be received fromthe power grid, converted to dc power, and then reconverted tocontrolled-frequency ac power by a switched inverter circuit. Devices ofthis type are used in conventional variable frequency drives, as well asin a variety of other products. Other applications include powerconverters, generators, power conditioning circuits, and so forth.

In conventional circuits based upon solid state power switches, theswitches may be controlled to switch between conductive andnon-conductive states extremely rapidly. Voltage spikes tend to occur,however, during turn-on stages of operation which can be detrimental tothe operation of the circuitry. That is, as the solid state switchingdevice is switched from a non-conducting state to a conducting state,such as to provide power to an output terminal, depending upon theconfiguration of the circuitry, large voltage spikes may occur which cancause damage to the switch and to other circuitry. In many cases,voltage spikes are caused by parasitic inductance in a dc circuit path,such as defined between elements of a dc bus used to convey power from arectifier circuit to an inverter circuit. Similar problems exist both insingle-phase circuitry and in three-phase circuitry.

While attempts have been made to improve performance of solid stateswitching circuits, additional improvement is necessary. For example,attempts have been made to place bus structures close to solid stateswitches to reduce the overall inductance of the bus. However, suchattempts have not been entirely successful, and may involve complexmechanical designs with limited actual impact upon reducing the voltagespikes in operation.

SUMMARY OF THE INVENTION

The present invention provides a novel bus design, and packagedcircuitry incorporating such designs which respond to such needs. Inaccordance with aspects of the technique, a bus structure is defined byconductive planes which are placed generally parallel to one another andseparate from one another and from neighboring conductors by insulativelayers. The bus structure may be formed to accommodate both-single phaseand multiple-phase circuitry. The technique facilitates unique packagingconfigurations, such as between switching devices and energy storagedevices, such as capacitors, that are positioned variously in an overallpackage configuration, such as on different sides of a support. The busstructure, which may be considered generally as a laminated bus, affordssubstantial reduction in parasitic conductance of the circuitry, whilefacilitating a variety of demanding packaging concerns, includingbending of the bus around circuit elements and mechanical supports. Thebus elements are designed to be disposed for direct connection to aconductor from power electronic switches.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other advantages and features of the invention willbecome apparent upon reading the following detailed description and uponreference to the drawings in which:

FIG. 1 is a circuit diagram illustrating, diagrammatically, an exemplarylaminated bus structure in accordance with aspects of the presenttechnique for a solid state switching circuit;

FIG. 2 is a diagrammatical representation of an implementation of thebus structure of FIG. 1 in a power electronics package;

FIG. 3 is a diagrammatical representation similar to FIG. 2 showing analternative arrangement for energy storage components in the package;

FIG. 4 is a perspective view of a portion of an exemplary implementationof the bus structure of the present technique as applied to a modulepower converter;

FIG. 5 is an exploded perspective view of the arrangement of FIG. 4,wherein an energy storage assembly and a terminal strip have beenremoved to better show the exemplary bus structure;

FIG. 6 is an exploded perspective view of the bus structure shown inFIG. 5, including conductive and insulative elements prior to assembly;

FIG. 7 is a front assembled view of the components of FIG. 6;

FIG. 8 is a bottom rear perspective view of the assembled component ofFIG. 7 and an exemplary terminal assembly to which the bus structure maybe joined;

FIG. 9 is top perspective view of the front of the bus structure andterminal assembly of FIG. 8 following assembly; and

FIG. 10 is a top perspective view of the rear of the assembly of FIG. 9illustrating pads to which switching components may be electricallycoupled for operation.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Turning now to the drawings, and referring first to FIG. 1, a bus system10 in accordance with the present technique is illustrateddiagrammatically as applied to a power converter circuit 12. The bussystem includes a pair of bus elements 14 and 16 which extend generallyparallel to one another in generally core extensive planes. It should benoted that, as described herein, the bus system is, in exemplaryembodiments, comprised of two generally parallel elements. However,additional elements, linked to one another or separate from one anothermay be provided in the alternative configurations. Similarly, while theelements are generally co-extensive with one another, some degree ofnon-overlap may occur in the elements, as described more fully below inan exemplary embodiment. Moreover, while the elements are described asextending generally in planes, it should be understood that the elementsare planar in so much as they are generally flat. A distinct advantageof the present technique, in fact, resides in the ability to configurethe bus system with flat flexible conductive and insulative elementssuch that the bus system itself can be bent or curved out of a singlegeometric plane.

In the illustration of FIG. 1, the bus system is applied to a convertercircuit that serves to convert three-phase line power to controlfrequency ac power for use in powering various loads. As will beappreciated by those skilled in the art, the configuration of FIG. 1 maygenerally correspond to an inverter drive, such as a three-phase motordrive. More generally, however, the present technique is applicable in awide range of settings, including converter circuits of the typeillustrated in FIG. 1, converter-converter circuits, generator circuits,power conditioning circuits, and any other power electronic circuit inwhich parasitic inductance is to be reduced in a dc bus coupled toswitching devices.

In the illustration of FIG. 1, the converter circuit example takes powerfrom a line or power grid as represented generally at reference numeral18, and applies the power to a rectifier circuitry 20. The rectifiercircuitry 20 may, in addition to rectifying the three-phases of power,perform additional functions such as filtering, voltage regulation, andso forth. The rectifier circuitry 20 applies dc power to a dc bus asrepresented at reference numeral 22 in FIG. 1. Various circuitry may beprovided across the dc bus, particularly for performing various powersignal filtering and energy storage functions. In the embodimentillustrated in FIG. 1, for example, energy storage circuitry 24 iscoupled across the dc bus 22, and may include a series of capacitors forstoring power and for smoothing power variations over the bus duringoperation. In the embodiment illustrated in FIG. 1, a three-phaseinverter circuit is provided across the dc bus, and includes a series ofsolid state switching devices 26, each paired with a flyback diode 28.Switching devices 26 may include any suitable type of switch, such asIGBTs, MOSFETs, and so forth. As will be appreciated by those skilled inthe art, by controlling switching of the switching devices 26, currentis caused to flow from the dc bus to a load 30. Appropriate switching ofthe devices, then, may result in desired waveforms being applied to load30, such as simulated three-phase ac forms of desired frequencies. Incertain applications, the switches may be controlled so as to provide asingle output frequency, such as for driving conventional loads at 60 Hzor 50 Hz.

It should be noted that, in certain presently contemplated arrangements,circuits other than rectifier circuits may be used in conjunction withinverter circuitry of the type shown in FIG. 1. For example, in certainvehicle drives, the rectifying circuitry illustrated in FIG. 1 may, infact, resemble the inverter circuitry shown. In a first power flowdirection, then, the circuitry would serve essentially as a rectifierfor providing dc power to the dc bus. In an opposite power flowdirection, however, the circuitry allow for switching, in a mannersimilar to that of switching devices 26, to clean and condition signals,such as in a regeneration mode. In such cases, the bus system describedherein may also extend to terminal locations for the switches of suchcircuitry.

In the embodiment illustrated in FIG. 1, the switches 26 are controlledby control circuitry 32 linked to driver circuitry 34. The controlcircuitry 32 may implement various control algorithms, such as forstarting sequences, shut-down sequences, steady-state operation, or anyother suitable control scheme. The driver circuitry 34 receives controlsignals from the control circuitry 32 and applies appropriate signals tothe switching devices 26 to regulate their operation. In general, thedriver circuitry 34 will cause the switches 26 to switch betweenconductive and non-conductive states for generating the desire to outputwaveforms. Sensor circuitry 36 may be provided for receiving varioussensor inputs, which may include electrical, mechanical, thermal, andany other suitable inputs for regulating the operation of the overallcircuitry. Conventional sensor circuitry may, for example, includefeedback of voltages, currents, speeds, indications of undesirableconditions, and so forth.

The bus system 10 illustrated in FIG. 1, preferably provides parallelconductive electrical reference planes which extend generally along oneanother for canceling parasitic inductance. In a presently preferredembodiment, the bus elements 14 and 16 define a continuous referenceplanes extending between terminations of the energy storage circuitryand terminations of the solid state switches. That is, the bus elementsmay be directly connected or coupled to a conductor extending from theswitches, rather than to any indirect interconnect, as in heretoforeknown devices. In other contexts, such as where filtering circuitry isprovided in lieu of or in addition to the energy storage circuitry 24,such planes might extend between the terminals of such circuitry andthose of the switching devices. It should be noted that, while a seriesof exemplary embodiments are described below, more generally, theparticular configuration, arrangement, dimensions, and spacing of thebus elements may be varied or specified depending upon specificoperating frequencies, voltage and current levels, properties of thematerials comprising the bus elements, and properties of materialsseparating the bus elements from one another and from neighboringcomponents. Thus, the bus system 10 can be tuned or engineered tooptimally adjust for transmission impedance, reducing the total loopinductance in a variety of circuit configurations.

FIG. 2 illustrates a portion of an exemplary configuration of the bussystem 10 in diagrammatical form. In the illustration of FIG. 2, asupport 38 for circuit components serves as a base for packagedswitching circuitry 40. The bus elements 14 and 16 essentially wraparound at least a portion of the support 38 and are electrically coupledto the switching circuitry 40, such as by single or multiple wire bonds,jumper cables, direct bonds and solder, or any other suitabletermination technique, as illustrated generally by reference numeral 42in FIG. 2. The bus elements extend to, and may include terminations forthe additional circuitry in the assembly, particularly capacitors 44which may form part of energy storage circuitry of the type illustratedat reference numeral 24 in FIG. 1. The embodiment of FIG. 2 allows forpre-forming of the bus structure with terminations made to the parallelbus elements upon installation.

As a variant or alternative to the structure of FIG. 2, FIG. 3illustrates a support 38 to which a similar switching circuitry package40 is mounted. Bus elements 14 and 16 again parallel to one another, areagain electrically coupled to the switching circuitry package. In theembodiment of FIG. 3, however, the bus extends in such a manner as todispose the capacitors 44 therebetween. As will be appreciated by thoseskilled in the art, various mechanical and electrical interconnectionarrangements may thus be envisaged.

It should be noted that in certain physical and electrical designs, thebus system may serve further circuitry. For example, multiple convertercircuits may be supported on different supports that share a common bussystem. Diagrammatically, referring again to FIGS. 2 and 3, anadditional support, similar to support 38, may be provided on a side ofcircuitry 24 opposite to the support 38 illustrated. The bus system thenmay extend to terminal locations for switching devices of the additionalconverter circuits.

FIGS. 4-10 illustrate aspects of a specific implementation of theinventive bus system. While the implementation is provided here forhighlighting particular potential features of the system, it should beborne in mind that the present system is not limited to this or anyspecific implementation. Indeed, many different circuits and physicalconfigurations may benefit from the present technique.

In the implementation of FIG. 4, a support 38 defines an electricalreference plane and supports a number of different circuit componentsinterconnected to form a modular power converter. A driver circuit board46 serves to receive control signals and applies drive signals to aseries of switching circuit assemblies 48. As noted above, the switchingcircuit assemblies 48 may output any desired waveforms, based upon thesignals received from control circuitry and from the driver circuitboard. The support 38 further supports a package energy storage orfiltering circuit 50 on a side opposite the drive circuit board 46 andswitching circuit assemblies 48. In the illustrated embodiment, thedevice is liquid-cooled, with a coolant inlet 52 being provided along aside of the support 38, and a coolant outlet 54 being provided besidethe inlet for conducting a stream of coolant to and from the support,thereby cooling the circuitry during operation.

The bus system 10, in the implementation of FIG. 4, is provided adjacentan edge of the support 38 for receiving input power and for transmittingoutput power from the device during operation. In particular, as will beappreciated by those skilled in the art, in the implementationillustrated in FIG. 4, a power converter of the type diagrammaticallyillustrated in FIG. 1 may be defined in which terminals linked to theswitching circuit assemblies 48 are electrically connected, as describedmore fully below, to terminals for the package energy storage circuitry50. The bus system 10, then, provides for significantly reducingparasitic inductance between these circuit components during operationas described more fully below.

As noted above, the present technique facilitates placement ofconnection areas or pads integral with the bus elements in closeproximity to the points where connections are made from the powerelectronic switches, as within assemblies 48 of FIG. 4. As will beappreciated by those skilled in the art, in prior arrangements, wherepackaged power electronic switching devices were employed, bus elementswere connected to an intermediate interconnect element, and therethroughto the switching devices, thereby introducing the potential forparasitic inductance. In the present technique, however, the connectionareas or pads may be “directly” coupled to the switching devices viasingle conductive link without the intermediary of an interconnect.Similarly, where the bus system of the present technique is used inconjunction with packaged power electronic devices, the bus elements maybe designed to extend into the package, so as to avoid the use ofinterconnects or similar intermediate structures that could introduceparasitic inductance.

In the implementation of FIG. 4, the bus system 10 is coupled to aterminal assembly 56 which serves to lead power to and from the device.In this embodiment, the terminal assembly 56, which is separable fromthe bus system 10, provides for electrical connection to the bus system,and to external circuitry via terminal conductors 58. Alternativeterminal structures may, of course, be envisaged, and the terminalstructures may be at least partially incorporated into the bus system asdescribed in the illustrated implementation below. Also, as noted above,an additional support 38 may be provided on a side of packaged energystorage circuitry 50, with the bus system being extended to terminallocations for the switching devices of additional converter circuitry.

FIG. 5 illustrates an exploded perspective view of the implementation ofFIG. 4. In particular, the packaged energy storage circuitry 50 has beenremoved from the support 38 to better illustrate how the exemplary bussystem 10 is interconnected between this packaged circuitry and othercircuit components. Moreover, in the illustration of FIG. 5, theterminal assembly 56 has been removed to show the exemplaryconfiguration of the bus system which is contoured to adapt to the edgeof the support 38 and to extend between the packaged energy storagecircuitry 50 and a location immediately adjacent to the switchingcircuit assemblies 48. The terminals for the energy storage circuitryare indicated in FIG. 5 by reference numeral 60. As can be seen, the bussystem accommodates directly linking these terminals to the bus system,and particularly to individual bus elements of the system as betterillustrated in the subsequent figures.

FIG. 6 illustrates a perspective view of the exemplary bus system 10 asapplied in the implementation of FIGS. 3 and 4, in an explodeddepiction. The exemplary system 10 includes flat bus elements 14 and 16configured conformingly with the application, separated from one anotherand from neighboring circuit components by insulative layers 62, 64 and66. As can be seen in FIG. 6, the bus elements 14 and 16 are generallyco-extensive with one another so as to aid in cancellation of parasiticconductance. The bus elements and insulative layers may be made of anysuitable material, with presently contemplated material for the buselements including aluminum or copper, and materials for the insulativelayers including sheet materials, such as a spun fiber materialcommercially available from E.I. du Pont de Nemours and Company underthe registered trademark Nomex. It has also been found that, wherecopper is used for the bus elements, bonding to conductors from thepower switching devices can be improved by providing aluminum pads inthe copper elements, such as areas of aluminum that are rolled, pressed,or otherwise disposed in recesses in the copper elements. Where copperconductors are bonded to the elements, copper could, of course, be usedfor the pads. Moreover, outer layers 62 and 66 may be eliminated fromthe structure, such as where no isolation is necessary.

As noted above, the various components of the bus system illustrated inFIG. 6 are preferably somewhat flexible, permitting them to beconformingly bent or pre-formed to follow desired contours. Also, thecomponents may be configured to present features which aide in isolatingthe bus elements from one another and from other components, and forconnecting the bus elements to circuitry. In the implementationillustrated in FIG. 6, for example, the insulative layers 62, 64 and 66are configured to extend beyond the extremities of bus elements 14 and16 slightly to provide edge isolation. Additional materials may beprovided in such areas, such as to further insolate the bus elementsfrom short circuits or other contact. Conversely, recesses are formed inthe insulative layers and in the bus elements themselves to allow forcontacts to circuitry. In the implementation illustrated in FIG. 6, forexample, recesses 66 are formed in insulative layer 64 to permit partialexposure of bus element 16 at locations where connections will be madeto circuitry. At similar locations, recesses 68 are formed in buselement 14 to expose bus element 16. Further recesses 70 are formed ininsulative layer 62 to expose both bus element 14 and bus element 16 inthe final stacked structure.

As noted above, the bus system may be pre-formed as a laminatedstructure, where desired. The final assembled system will permitconnections where desired, and may be configured in various pre-formedgeometries. FIG. 7 represents a finished geometry for the exemplaryimplementation shown in FIG. 6. In the view of FIG. 7, the bus elements14 and 16 have been assembled with insulative layers 62, 64 and 66. Itshould be noted that at alternate locations, owing to the positions ofthe recesses discussed above with reference to FIG. 6, both bus element14 and bus element 16 are accessible through the stacked layers.Similarly, termination tabs 72 are provided extending from both buselements to permit further attachment, in this implementation to theterminals 60 of the packaged energy storage circuitry (see FIG. 5).Finally, additional insulative material, which may be an extension ofone or more insulative layers may be wrapped around one or more of thebus elements as indicated at reference numeral 74 in FIG. 7 to provideadditional isolation, where desired.

The laminated structure may be formed by adding a suitable adhesivelayer between the bus elements and the insulative layers, as well asalong any edges where the insulative layers meet and may be joined. Theassembled elements and layers may then be pressed and heated, dependingupon the requirements of the adhesive layers, to form a tightlylaminated structure. While the laminated structure may be bent, formedor otherwise contoured so some extent, such contouring may befacilitated if performed prior to the lamination of the elements andlayers.

The bus structure may then be assembled with other circuit components,as illustrated in FIG. 8. In the implementation of FIG. 8, the bussystem 10 is assembled with the terminal assembly 56 described above. Inparticular, in this implementation the bus system 10 is stacked with thepre-assembled terminal assembly 56 such that bottom surfaces 76 of theterminal conductors are positioned adjacent to portions of insulativelayer 62 between which the exposed bus element portions are provided(see FIG. 7). Following such assembly, as illustrated in FIG. 9, the bussystem and terminal assembly exposes termination tabs 72 of the bussystem, as well as terminal conductors 58 of the terminal assembly for aconnection to the packaged energy storage circuitry and to externalcircuitry, respectively. Furthermore, as shown in FIG. 10, along a rearside of the bus system 10 and terminal assembly 56, a series ofconnection pads 78 are exposed corresponding to locations of both thebus element 14 and bus element 16, and to portions of the terminalconductors 58. Thus, direct connection, such as via wire boning, can bemade to the other circuit elements, including to the switching circuitassemblies 48 illustrated in FIG. 4 and discussed in detail above.

As will be appreciated by those skilled in the art, then, the unique bussystem of the present technique allows for contiguous generally parallelbus elements which can extend completely between terminal locations forswitching devices and terminal locations for other circuitry, such asfiltering circuitry, energy storage circuitry, and the like. Wheredesired, certain elements of the system may extend into and throughcertain of these circuit assemblies, particularly through the filteringand energy storage circuitry in a manner discussed above generally withreference to FIGS. 2 and 3. Also, as noted above, the bus elements maybe designed to extend into packaged switching devices to avoid the needfor interconnects.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

1. An electrical bus system comprising: a first conductive bus elementdefining a first electrical reference plane extending substantiallycontiguously between a terminal for a first conductor coupled directlyto power electronic switching circuitry and terminals for an energystorage or filtering circuit; a second conductive bus element defining asecond electrical reference plane extending substantially contiguouslybetween the terminals for a second conductor coupled directly to thepower electronic switching circuitry and the terminals for the energystorage or filtering circuit; at least one insulative layer disposedintermediate the first and second bus elements to electrically isolatethe elements from one another; wherein the first and second bus elementsextend generally in parallel between the respective terminals to reduceparasitic inductance during operation
 2. The bus system of claim 1,wherein the bus elements and the insulative layer form a laminatestructure.
 3. The bus system of claim 1, further comprising at least oneadditional insulative layer disposed adjacent to the first or the secondbus element for electrically isolating the bus element from adjacentcomponents.
 4. The bus system of claim 1, wherein the first bus elementand the insulative layer include recesses for accessing connection areasof the second bus element.
 5. The bus system of claim 1, wherein thefirst and second bus elements include integral connection areas forelectrically coupling the bus system to power electronic switchingcircuitry for three phases of ac power.
 6. An electrical bus systemcomprising: a first conductive bus element defining a first electricalreference plane extending substantially contiguously between a terminalfor a first conductor coupled directly to power electronic switchingcircuitry and terminals for an energy storage or filtering circuit; asecond conductive bus element defining a second electrical referenceplane extending substantially contiguously between a terminal for asecond conductor coupled directly to the power electronic switchingcircuitry and the terminals for the energy storage or filtering circuit;an inner insulative layer disposed intermediate the first and second buselements to electrically isolate the elements from one another; andfirst and second outer insulative layers disposed adjacent to the firstand second bus elements, respectively, opposite the inner insulativelayer, to electrically isolate the elements from other components;wherein the first and second bus elements extend generally in parallelbetween the respective terminals to reduce parasitic inductance duringoperation.
 7. The bus system of claim 6, wherein the bus elements andthe insulative layers are contoured to conform to at least one supporton which the power electronic switching circuitry and energy storage orfiltering circuit are mounted.
 8. The bus system of claim 6, wherein thebus elements and the insulative layers form a laminate structure.
 9. Thebus system of claim 6, wherein the first bus element and the insulativelayers include recesses for accessing connection areas of the second buselement.
 10. The bus system of claim 6, wherein the first and second buselements include integral connection areas for electrically coupling thebus system to power electronic switching circuitry for three phases ofac power.
 11. An electrical bus system comprising: a first conductivebus element defining a first electrical reference plane extendingsubstantially contiguously between a terminal for a first conductorcoupled directly to power electronic switching circuitry and terminalsfor an energy storage or filtering circuit; a second conductive buselement defining a second electrical reference plane extendingsubstantially contiguously between a terminal for a second conductorcoupled directly to the power electronic switching circuitry and theterminals for the energy storage or filtering circuit; an innerinsulative layer disposed intermediate the first and second bus elementsto electrically isolate the elements from one another; and first andsecond outer insulative layers disposed adjacent to the first and secondbus elements, respectively, opposite the inner insulative layer, toelectrically isolate the elements from other components; wherein thefirst and second bus elements extend generally in parallel between therespective terminals to reduce parasitic inductance during operation,and wherein the bus elements and the insulative layers form a laminatestructure and are contoured to conform to at least one support on whichthe power electronic switching circuitry and energy storage or filteringcircuit are mounted.
 12. The bus system of claim 11, wherein the firstbus element and the insulative layers include recesses for accessingconnection areas of the second bus element.
 13. The bus system of claim11, wherein the first and second bus elements include integralconnection areas for electrically coupling the bus system to powerelectronic switching circuitry for three phases of ac power.
 14. A powerelectronic switching device comprising: power electronic switchingcircuitry having a plurality of terminals; first and second conductorscoupled directly to the terminals of the switching circuitry; an energystorage or filtering circuit having a plurality of terminals; and anelectrical bus system comprising a first conductive bus element defininga first electrical reference plane extending substantially contiguouslybetween the first conductor and the terminals for the energy storage orfiltering circuit, a second conductive bus element defining a secondelectrical reference plane extending substantially contiguously betweenthe second conductor and the terminals for the energy storage orfiltering circuit, and at least one insulative layer disposedintermediate the first and second bus elements to electrically isolatethe elements from one another, wherein the first and second bus elementsextend generally in parallel with one another between the respectiveconductors and terminals.
 15. The device of claim 14, wherein the buselements and the insulative layer form a laminate structure.
 16. Thedevice of claim 14, further comprising at least one additionalinsulative layer disposed adjacent to the first or the second buselement for electrically isolating the bus element from adjacentcomponents.
 17. The device of claim 14, wherein the first bus elementand the insulative layer include recesses for accessing connection areasof the second bus element.
 18. The device of claim 14, wherein the firstand second bus elements include integral connection areas forelectrically coupling the bus system to power electronic switchingcircuitry for three phases of ac power.
 19. The device of claim 14,wherein the bus elements each comprise integral connection areas forelectrically coupling the bus elements and the terminals of the energystorage or filtering circuit to a source of dc power.
 20. A powerelectronic switching device comprising: power electronic switchingcircuitry having a plurality of terminals and configured to receive dcinput power and to generate ac output power; conductors coupled directlyto the terminals of the power electronic switching circuitry; an energystorage or filtering circuit having a plurality of terminals andconfigured to be coupled to a source of dc power; and a dc bus systemcomprising a first conductive bus element defining a first electricalreference plane extending substantially contiguously between a first setof the conductors and the terminals for the energy storage or filteringcircuit, a second conductive bus element defining a second electricalreference plane extending substantially contiguously between a secondset of the conductors and the terminals for the energy storage orfiltering circuit, and at least one insulative layer disposedintermediate the first and second bus elements to electrically isolatethe elements from one another, wherein the bus elements each compriseintegral connection areas for electrically coupling the bus elements tothe conductors, and to the terminals of the energy storage or filteringcircuit and the source of dc power, wherein the first and second buselements extend generally in parallel with one another between therespective conductors and terminals to substantially reduce theparasitic inductance and total loop inductance in the device.
 21. Thedevice of claim 20, wherein the bus elements and the insulative layerform a laminate structure.
 22. The device of claim 20, furthercomprising at least one additional insulative layer disposed adjacent tothe first or the second bus element for electrically isolating the buselement from adjacent components.
 23. The device of claim 20, whereinthe first bus element and the insulative layer include recesses foraccessing connection areas of the second bus element.
 24. The device ofclaim 20, wherein the first and second bus elements include integralconnection areas for electrically coupling the bus system to powerelectronic switching circuitry for three phases of ac power.
 25. Amethod for reducing parasitic inductance in a power electronic switchingdevice, the method comprising: defining a first substantially contiguouselectrical reference plane of a dc bus for coupling between a firstconductor directly coupled to a power electronic switching circuitry andterminals for an energy storage or filtering circuit; defining a secondsubstantially contiguous electrical reference plane of the dc bus forcoupling between a second conductor directly coupled to the powerelectronic switching circuitry and the terminals for the energy storageor filtering circuit, the second electrical reference plane extendingparallel to the first reference plane to reduce inductance in the deviceduring operation; and electrically isolating the first and secondreference planes from one another.
 26. The method of claim 25, furthercomprising electrically isolating the reference planes from adjacentcomponents of the device.
 27. The method of claim 25, comprisinglaminating the reference planes with at least one isolating layer toform a laminated structure.
 28. The method of claim 25, furthercomprising providing integral connection areas of the reference planesfor coupling the reference planes both to a source of dc power and tothe terminals of the energy storage or filtering circuit.
 29. The methodof claim 25, further comprising contouring the reference planes and anintermediate isolation layer to conform to a support.
 30. A system forreducing parasitic inductance in a power electronic switching device,the system comprising: means for defining a first substantiallycontiguous electrical reference plane of a dc bus for coupling between afirst conductor coupled directly to a power electronic switch andterminals for an energy storage or filtering circuit; means for defininga second substantially contiguous electrical reference plane of the dcbus for coupling between a second conductor coupled directly to thepower electronic switch and the terminals for the energy storage orfiltering circuit, the second electrical reference plane extendingparallel to the first reference plane to reduce inductance in the deviceduring operation; and means for electrically isolating the first andsecond reference planes from one another.